The present invention relates to a stepladder capable of reducing the risk of toppling.
Conventionally, stepladders are used in light work at height, for example, pruning of tree branches. A tripod stepladder and a four-legged stepladder are known as such stepladders. For example, a conventional four-legged stepladder 20 shown in FIG. 11 includes a front leg pair 21 and a rear leg pair 22, which are shaped as ladders. The front and rear leg pairs 21 and 22 are coupled to each other. The distance between the ground contact points of left and right legs 21L and 21R of the front leg pair 21 and the distance between the ground contact points of left and right legs 22L and 22R of the rear leg pair 22, or the widths, are fixed. Further, the distance between the ground contact point of the front left leg 21L and the ground contact point of the rear left leg 22L is fixed, and the distance between the ground contact point of the front right leg 21R and the rear right leg 22R is fixed. The taller the type of stepladder, the greater the width of the stepladder becomes.
FIG. 12 shows a conventional four-legged stepladder 23 including a front left leg 21L, a front right leg 21R, a rear left leg 22L, and a rear right leg 22R that have adjustable lengths. Thus, even if there is a slight unevenness in the installation location, the height of each leg can be changed in conformance with the unevenness.
FIG. 13 shows a conventional tripod stepladder 25 that includes a ladder-shaped front leg pair 23 and a bar-shaped rear leg 24. The front leg pair 23 includes a front left leg 23L and a front right leg 23R that are fixed to form a predetermined width. The taller the type of stepladder, the greater the width of the stepladder becomes.
Besides the conventional stepladders shown in FIGS. 11 to 13, stepladders described in Patent Documents 1 to 3 are known.
However, in the conventional four-legged and tripod stepladders, increase in the distance between the front legs and the rear leg(s) or increase in the width between the left and right legs of the front leg enlarges the footprint of the stepladder. Thus, even when the height of a stepladder is increased in accordance with the purpose and type, increase in the width tends to be restrained. As a result, a higher stepladder has a higher risk of lateral toppling.
Moreover, in the conventional four-legged and tripod stepladders, the front and rear legs spread only to the front and rear. Reduction in the angels between the supports of the front and rear legs and the horizontal installation surface does not reduce the risk of lateral toppling. Furthermore, the legs of the ladder that function as the front legs have a large width. This prevents setting of the legs of the ladder in narrow space, such as a place where various items of equipment are already installed and a place with hedges. In addition, since the front and rear legs are fixed, the stepladder cannot be set in a place including facility pipes or tree branches above the ground or in a place having significant slopes or unevenness.